Hydrofoil steering, adjusting and retracting mechanism



May 19, 1959 H, BOERICKE, JR., ETAL 7,

HYDROF OIL STEERING, ADJUSTING AND RETRACTING MECHANISM Filed Aug. 31.1956 4 Sheets-Sheet 1 INVENTORS HAROLD BOERICKE JR JOHN BADER ATTORNEYSMay 19, 1959 H. BOERICKE, JR., ETAL 2,887,082

ADJUSTING AND RETRACTING MECHANISM HYDROFOIL. STEERING,

Filed Aug. 31, 1956 4 Sheets-Sheet 2 INVENTORS HAROLD EOERICKE, JR, JOHNBADER ATTORNEYS y 1959 H. BOERICKE, JR. ETAL 2,887,082

HYDROFOIL STEERING, ADJUSTING AND RETRACTING MECHANISM 4 Sheets-Sheet 3Filed Aug. 31, 1956 INVENTORS n E R J W m E 7 W m M A m OD 4 BA fi B L Nw J y 9, 1959 H. BOERICKE, JR, EFAL 2,887,082

HYDROFOIL STEERING, ADJUSTING AND RETRACTING MECHANISM Filed Aug. 31,1956 4 Sheets-Sheet 4 S 5 m8 n T N NJ R E 7O VE W NK RR 2 m x A D L N 8w MJ United States Patet HYDROFOIL STEERING, ADJUSTING AND RETRACTINGMECHANISM Harold Boericke, 31"., and John Bader, Washington, D.C.

Application August 31, 1956, Serial N0. 607,529

17 Claims. (ci. 114-665 (Granted under Title as, US. Code 1952 see. 266)The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or therefor. p

This invention relates to improvements in hydrofoil craft and inparticularit relates to steering, angle of attack control andindication, and to retraction of hydrofoils.

Existing mechanisms for supporting forward foils on a craft are mountedon the ends of fixed arms extending from the sides of the craft. Suchmechanismsmake no provision for steering by the forward foils. With suchmechanisms, any adjustment to the angle of attack of the foils isawkward and cumbersome. Such mechanisms are relatively inaccessible andthe fixed arms are a constant source of annoyance and damage while thecraft is lying alongside a dock or the like. The structures usedheretofore allow the foils to be jarred out of adjustment, and no simplecheck is possible for realignment while waterborne. Realignment is atedious process which, with existing mechanisms, can be done only afterthe craft has been hauled out of the water.

With the above in view, a principal object of this invention is theprovision of a single, interconnected mechanism for steering,controlling and indicating angle of attack, and

for retracting hydrofoils, which are mounted on the sides of the hulland are accessible from the deck of hydrofoil craft.

Another object of the invention is the provision of automatic angle ofattack control for hydrofoils while steering by such foils.

Another object of the invention is the provision for retraction close tothe hull and out of the water of'foils of a hydrofoil craft while suchcraft is waterborne.

Another object of the, invention is the provision of balance of lift anddrag foiltorques in hydrofoil craft.

Another objectof the invention is the provision of a safety device forlimiting stresses imposed on the mechanism in case of foil impact on afloating object or the like.

A further object of the invention is the provision of synchronizingmechanism for simultaneous movement of hydrofoils mounted on oppositesides of a craft.

The invention, together with the above and other objects and advantagesthereof, is set forth in more technical detail in the followingdescription and accompanying drawings, wherein:

Fig. 1 is a schematic top planview, partly in section, of a water craft,showing a pair of hydrofoils attached to opposite sides of the hull nearthe bow thereof and a hydraulic system for manipulating the foils inaccord ance with this invention;

on the gudgeons forrot ation about a near-vertical axis.

ice

Fig. 5 is a top plan view of the structure shown in Fig. 2;

Fig. 6 is a vertical section taken on line 6-6 of Fig. 5;

Fig. 7 is a transverse section taken on line 7--7 of Fig. 6;

Fig. 8 is a transverse section taken on line 8-8 of Fig. 6; and

Fig. 9 is a side elevational view of the structure shown in Fig. 2, andshowing in broken lines the relative retracted position of thehydrofoil.

Referring now to Fig. 1 of the drawing wherein for purposes ofillustration there is shown the forward portion of a water craft 10having a pair of forward hydrofoil mechanisms 12 and 12' mounted onopposite sides of the hull near the bow thereof. Suitable aft hydrofoilmechanisms, not shown, may be mounted, near the stern of the craft. Thehydrofoil mechanisms 12 and 12'. are operated by a pair of hydraulicrams 14 and 14', respectively, which rams are connected by pairs ofconduits 16, 16' and 18, 18' to opposite ends of a pair of hydraulicsteering cylinders 20 and 20, respectively. The hydraulic steeringcylinders are mounted on opposite sides of a control box 22 and areprovided with pistons 24, 24 and piston rods 26, 26, which piston rodsare connected to opposite ends of a gear rack 28 for reciprocationtherewith. A pinion gear 30, mounted on the forward end of a steeringshaft 32, meshes with rack 28. The steering shaft is journaled on thecontrol box and has a steering. wheel 34 mounted on the aft end thereof.A' solenoid-operated retracting plunger 36 is mounted Within the controlbox and includes a piston 37 mounted within a hydraulic cylinder 33,which cylinder has conduits 40 and 42 connected to opposite endsthereof. Conduit 40 is provided with a solenoid-operated valve 41 havinga pair of branches a and 4012 leading therefrom andconnected,respectively, to conduits 16 and 16'. Conduit 42 is provided with asolenoid-operated valve 43 having a pair of branches 42a and 42b leadingtherefrom and connected, respectively, to conduits 18 and .18.

Plunger 36, when deenergized, is spring-biased to the inner positionshown in Fig. l, and when energized, piston 37 is forced outwardly ofcylinder 38. Solenoidoperated valves 41 and 43 are biased to closedposition when deenergized and are open when energized. So that theplunger and the solenoid valves may be operated simultaneously, they arewired in series in an electric circuit. This circuit includes a leadwire 45 leading from a suitable source of current, a switch 46, solenoidplunger 36, solenoid valve 43, solenoid valve 41 and a return wire 47back to the source of current. A switch bridge 48 for closing switch 46is mounted on rack 28 and is positioned in a manner to close the switchterminals and thereby energize the plunger and valves when the steeringwheel is rotated clockwise beyond a given steering range. For preventingaccidental rotation of the steering wheel beyond this steering range, asuitable stop mechanism, not shown, may be provided. Thus, as will bedescribed in detail hereinafter, the hydrofoil mechanisms 12 and 12aresimultaneously moved to their retracted position by clockwiserotation of the steering wheel-beyond its steering range. Hydrofoilmechanisms 12 and 12' are similar, but of opposite hand, therefore, onlyone such mechanism 12, will be described in detail.

Referring now to Figs. 2, 5 and 6, hydrofoil mechanism 12 includes asubstantially triangular-shaped frame 50 mounted on the hull of thecraft by a pair of gudgeons 51 and 52. Frame 50 includes a near-verticaltubular inemberSS, a horizontal tubular-member 54 and connecting struts55 and 56. A near-vertical shaft 58, that passes through tubular member53, mounts the frame H 'A horizontal shaft 59 passes through tubularmember 54 of the frame and has a hydrofoil 60 rigidly attached theretofor rotation therewith. A bevel gear 62 attached to the inboard end ofhorizontal shaft 59 meshes with a segment of a companion bevel gear 63formed on a lower portion of near-vertical shaft 58.

The hydrofoil 60 may be of any desired form, however, ,for purposes ofillustration, it is shown here as a diamend-shaped foil in accordancewith the invention of Harold Boericke, In, one of the joint inventorsherein, and described in his application, Serial No; 555,212, filedDecember 23, 1955.

As'shown in Fig. 2, the hydrofoil comprises a unitary structureincluding an upper or inverted V-shaped foil 64, a lower V-shaped foil65 and a horizontal foil and brace 66. The hydrofoil is attached to theoutboard end of shaft 59 by a strut 67, which, as shown in Figs. and

9, extends upward and aft from the top V and terminates in a collarrigidly secured to shaft 59, and at the inboard corner, the hydrofoil issupported by a strut 68 also rigidly secured to the shaft. Thus, asshown in Figs. 5 and 9, the hydrofoil is supported on a horizontal axison a line to the rear of the plane of the foils so that the lift forcesof the foils tend to rotate the bottom of the hydrofoil forward. Thistends to counter-balance the effects of drag forces of the hydrofoiltending to rotate the bottom of the hydrofoil aft. In this manner,hydrodynamic balance is obtained. For a more detailed description of thediamond-shaped hydrofoil and modifications thereof, reference may be hadto the above patent application of Harold Boericke, Jr., Serial No.555,212.

' Returning to Figs. 2 and 6, the frame 50, and hydrofoil 60 attachedthereto, is made to rotate with and about 'the near-vertical shaft 58 bya steering arm 70, as dejjscribed hereinafter. Arm 70 has an outboardend thereof keyed, as by keys 71, to the upper portion of frame member53 and an inboard end pivoted, as by pivot pin 72 (Fig. 5), to abifurcated end 73 of a piston rod 74, which piston rod is attached to apiston 75 within a cylinder 76 of hydraulic ram 14. So that the cylinderof the hydraulic ram may be free to move with movement of the piston andpiston rod, the cylinder is pivoted to the deck of the craft by a pivotconnection 78.

An arm 80, for adjusting the angle of attack of the hydrofoil, ismounted on top of steering arm 70 and has an outboard end thereof thatsurrounds shaft 58 and is releasably attached thereto by a clutch member90. The inboard end of arm 80 is formed as a segment of a gear 82 (Fig.7) that meshes with a worm gear 84. Gear 84 is provided with a shaft 85journaled in a pair of supports 86 formed on steering arm 70. A crank87, for manually rotating the worm gear and through it the adjusting arm'80, is mounted on one end of shaft 85.

The upper portion of near-vertical shaft 58 is formed 'with a portion58a (Figs. 3 and 6) of reduced diameter upon which is mounted a splinedsleeve 91. A safety or rotation therewith.

As shown in Figs. 2 and 7, clutch member 90 is formed with a pair ofkeys or projections 93 on the lower face thereof, which keys fit intokeyways 94 in the upper face of adjusting arm 80. For moving the clutchmember 90 vertically relative to the adjusting arm and therebydisengagingthe adjusting arm from shaft 58, a roller 95 -is mounted onone side of the clutch member in position to ride upon a ramp surface96a of a cam member 96,

which cam member forms a part of the upper gudgeon 51 (Figs. 2 and 3).Clutch member 90 is formed with an upper portion 90a of reduced diameter(Fig. 6) for the reception of a coil spring 97, which spring. releasahlyv, 4 urges the clutch member into engagement with the adjusting arm andis itself held under compression by a washer 98 and a nut 99, the latterscrew-threaded upon the upper end 58a of shaft 58. A stop 52a, formed onlower gudgeon 52 (Figs. 2 and 4), contacts a vertical surface 63a formedon bevel gear 63 and thereby limits forward rotation of the combinedframe and hydrofoil mechanism 12 within the forward steering rangethereof. The stop 52a, upon stopping forward rotation of the frame andhydrofoil mechanism, also initiates the retraction of the hydrofoil, aspointed out hereinafter.

In operation, with the hydrofoils athwartship,as shown in Fig. l,clockwise rotation of the steering wheel, through the rack and pinion,causes piston 24 to be moved inward of cylinder 20 and hydraulic fluidto be forcedfrom the cylinder through conduit 18 into hydraulic ram 14behind the piston therein, with the result that the piston is forcedinwardly of the cylinder and hydrofoil mechanism 12 is rotated aft ofthe craft. Simultaneously with the forcing of fluid from cylinder 20,fluid is forced from cylinder 20' through conduit 16' into hydraulic ram14 in front of the piston therein, with the result that this piston isforced outwardly of the cylinder and hydrofoil mechanism 12' is rotatedforwardly to the craft; thus, the craft makes a starboard turn.Counterclockwise rotation of the steering wheel causes forward rotationof hydrofoil mechanism 12 and aft rotation of hydrofoil mechanism 12';whereupon, a port turn is maneuvered. The steering range of thehydrofoil mechanisms is approximately eight degrees fore and aft ofathwartship. It will be noted that each of the hydraulic systems thusfar described constitutes a closed circuit so that the forcing of fluidfrom one end of a cylinder causes fluid to flow into the opposite endthereof, and vice versa. -Since valves 41 and 43 are closed duringsteering maneuvers, fluid cannot by-pass through branch conduits 40a,405 or 42a, 42b. 1

With the clutch 90 engaged, as shown in Figs. 2 and 6. frame 50,near-vertical shaft 58, horizontal shaft 59, bevel gears 62 and 63, andhydrofoil are held fixed relative to each other, so that through thesteering range of approximately eight degrees fore and aft ofathwartship these components rotate about the near-vertical axis as aunit. The steering range of movement of the piston 75 fore and aft thecylinder 76 of hydraulic ram 14 is approximately that shown'in Fig. 5.That is, the capacity of hydraulic cylinder 20 (Fig. 1) is such that,with maximum clockwise movement of the steering wheel in the steeringrange, sufficient fluid is forced from cylinder 20 through conduit 18into cylinder 76 to force piston 75 from the position shown in Fig. 5 tothe inner end of the cylinder. Conversely, with maximum counterclockwiserotation of the steering wheel in the steering range, sufficient fluidis forced from cylinder 20 through conduit 16 into cylinder 76 to forcepiston 75 from the position shown in Fig. 5 a like distance outwardly ofthe cylinder. This latter movement of piston 75 causes steering arm torotate frame and hydrofoil mechanism 12 forwardly about thenear-vertical axis until the vertical surface 63aon bevel gear 63contacts stop 52a on gudgeon 51 which limits this forward movement andpositions the mechanism 12 for retraction of hydrofoil 60.

In retracting the hydrofoils, the steering wheel is rotated clockwisebeyond the steering range and until bridge member 48 closes the electriccircuit through switch terminals 46, the solenoid-operation valves 41and 43 (Fig. l) in conduits 40 and 42, which. are closed during steeringmaneuvers, are energized and'opened and the solenoid-plunger 36 isenergized so that now hydraulic fluid is forced from cylinder 38 throughconduit 40, branches 40a and 40b, and conduits 16 and 16 into thecylinders of rams 14 and 14', respectively, in front of the pistonstherein. In the meantime the steering wheel and its rack and pinion willhave been locked by suitable mechanism, not shown, so that the forcingof fluid from retraotingcylinder 38: \vilLhaveno effect on the position;of thepistonsin steering. cylinders. 20=and 20. It may be statech thatthe. retracting; maneuver. is. best: initiated with the frame and.hydrofoil mechanisms positioned. athwartship, asshown in; Fig. 1.

Withthe frame and hydrofoil mechanism so positioned and hydraulic fluidbeing forced. from; cylinder. 38 into the cylinders of rams 14 and.14,as just described, the pistons ofsuch cylinders are moved outwardlythereof (aft of the craft) Whereuponthe frame and hydrofoil mechanisms12 and 12 are each rotatedabout its near-vertical axis forwardly of thecraft. The capacity of cylinder 33 is such that now the pistons of rams14 and 14. are moved beyond the forward steering range to the aft end oftheir cylinders.-

In tracingtheretracting movement of frame and hydrofoil mechanismlZ, forexample, the.above extrememovement of. piston 75 causes arm 70 to rotatethe frame and hydrofoil, mechanism forward of the craft as a unit. Asframe Stlmoves beyond the forward end of the steering range,theverticalsurface. 63a on bevel gear 63, strikes the stop 52a on thelower gudgeon (Figs. 2 and 4) causing gear. 63 and consequently shaft 58to be held stationary. At thisipoint the roller 95 on clutchmember90-ridesup the ramp 96:: (Fig. 3) of cam 96 which disengages the clutchand: allows the frame 50 torotaterelative to bevel gear 63 and shaft 58.As the ram continues .torotatethe frame forward, the now stationarybevel gear 63, through the meshing gear 62, causes horizontal shaft59'to rotate hydrofoil 60 backwards and upwards at a rate, determined bythe gear ratio, of slightly morethan twice that of the frame. Thus, asaresult of a frame rotationof 80 forward, the hydrofoil rotates 180backwards and upwards, describing a simultaneous and combined rotation.At the end of this travel, the foil frame retracts to a forwardposition, against the hull of the craft, whereas: thehydrofoil itselfrotates into a. nearly-vertical up-side down position in line with thenear-vertical axis of rotation of the foil frame, as shown in brokenlines in Fig. 9.

The lower plate of the clutch is apart of the angleof attack control arm80 that is regulated by the worm gear 84. The upper plate of the clutchis restrained in rotation by the splined sleeve 91 on the near-verticalshaft 58', and it is restrained in, vertical motion by compressionspring97 acting on its upper surface. The safety pin 92. (Fig. 3) isincorporated between the. splined. sleeve 91 of the upper clutch plateand the reduced portion 58a of shaft 58 to limit impact on the foil.That is, should the foil strike a floating object,'the pin 92 issheared, thereby relieving the mechanism of undue strain. To realign thehydrofoil, it is required only to use a portable wrench on the top ofshaft 58 to reset the foil and replace the safety pin. This operationcan be performed'while afloat.

The angle of attack of hydrofoil 60 may bechanged with respect to theframe 50 by means of worm gear 8.4, attachedto arm 80. Rotation of thewormgear by crank 37rotates arm 80, clutch 90 and shaft 58, with respectto frame 50. Through bevel gears 62 and 63, shaft 58 rotates shaft 59and thus hydrofoil 60. All this takes place while frame 50 is held inone position by arm 70 and ram-14. A feature which permitsautomaticangle of attack change for controlof the bankwhile turning is the,inclination of the near-vertical shaft 58 up and outboard (Figs. 2 and6). While steering, the hydrofoil on the outside of the turn movesforward, and the (hydrofoil'on the inside of the turn moves aft. The upand outboard inclinations. ofjthe vertical; axis: of the hydrofoilframes, cause the foil angle of. attackto; increase-. on the outboardside of" the turn and decrease on the inboard side, thus increasing thelift on the outboard foil and decreasing it on the inboard foil. Thedifference in the lift forces on the two foils causes an inboard-bankingmoment which opposes the outboard-banking moment on inboardhydrofoilwhile maneuvering the-boat stcentrifugalforce on the turn. The. angle.which this. axis of; rotation makes with/the. vertical determines the:amountfofinboard-banking moment of the foils,,a nd sodeterminesv howmuchthe boat. banks. inboard. or out;- boardI onr a: turn.

A. featurewhich reduces. the size of the shafts, bevel gearsand, clutchmembers, is the torquevbalancing effect of the foils forward of the foilframe. In flight,. the forward-rotating moment of. the lift causedbythe. offset strut 6.7 counteracts, or more. than. counteracts the aft?rotating moment about a horizontal: axis in the foil frame of the drag,thusleaving a small residual. momentto. be controlled. by, the gears 82and84, noted above. If the. lift torque, forward. more. thancountenbalances the. dragtorque ate, the net torque is then forward, andit provides a ,cushionfor, impact on the foils. The impact, when-thefoils strike an object, has first to overcome the nettorque forwardbefore it acts on.the shear pin.

As. will nowbe seen, the hydrofoil steering, retracting and adjustingmechanismis relatively compact in.con-. figuration, allowing. thefoilsto retract close to the hull out of the water and thus avoid damage tosuch foil mechanism. Themechanism is. integratedto a degree of allowingall necessary functions to be accomplished with. less. partsthanheretofore required. The mechanism distributes the lift forcesandmoments of the foils to the hull in a wider and more effectivemanner, 'utilizingsexisu ing structural members ofthe hull to fulladvantage. Also, the angle of attack and position ofthe foils isadjusted and indicated. in a positive manner from the deck of the boatwhile. waterborne.

Without further descriptiomit is thought that the fear. tures andadvantages, oftheinvention will be readilyapparentto. those. skilled in.the art to. which thisinventiou appertainsand, it will, of course, beunderstood that; while.but.-,oue. embodiment of the invention has beenlllUSr trated. and. described herein, changes in form, proportionsandminon details. of construction may be resorted to .with.outdepartingfrom the spirit of the invention and, scope of the claims.

Whatis claimed is:

l. A hydrofoil craft comprising a hull, a pair of hydro.- foilsforsupporting the craft in motion, means mounting said hydrofoilsonopposite sidesof the hull for rotary,

movement fore and. aft thereof, steering mechanism mounted on the craft,and means connecting thesteering mechanism to each of the hydrofoils ina manner as to rotate the hydrofoilsin opposite directions fore and aft,of the hull'with movement of the steering mechanismtothereby. steer. thecraft by the hydrofoils.

2. A hydrofoil craft as set forth in claiml which ineludes means forchanging the angle of attack of the; hydrofoils. while steeringtherewith and in a manner as to increase the angle of attack oftheforwardly moving or outboard hydrofoil and to decrease the angle of at-itack on the aft moving or inboard hydrofoil, thus increas-:

ing, lift, of. the outboard hydrofoil and. decreasing liftof the inboardhydrofoil while maneuvering a turn.

31 A hydrofoil craft as set forth in claim 1 wherein the means rotatablymounting the hydrofoils include a rotatable frame mounted on anear-vertical axis upward. and outboard of .the hull at each sidethereof, whereby the. angle of attack is increased on the forwardlymovingqor outboard hydrofoil and isdecreased on the aft moving or aturn.

4. A hydrofoil craft as set forth in claiml whereinthe. means rotatablymounting the hydrofoils and the steering. mechanism include meansoperative to limit. thefore and aft movement of the hydrofoils. within asteering range.

5. A hydrofoil craft as set forth in claim l wherein'the. meansrotatably mounting the hydrofoils include means for retracting thehydrofoil mechanisms clear of a body of water upon which the craft isborne.

6. A hydrofoil craft comprising a hull including a deck, a pair ofhydrofoil mechanisms rotatably mounted on opposite sides of the hull,said hydrofoil mechanisms being similar but of opposite hand, steeringmechanism mounted on said deck, and means connecting the steering mecha-'nism-to each of the pair of hydrofoil mechanisms in a manner as torotate said hydrofoil mechanisms in opposite directions fore and aft ofthe hull with movement of the steering mechanism to thereby steer thecraft by the hydrofoil mechanisms.

7. A hydrofoil craft comprising a hull, a pair of hydrofoils, meansrotatably mounting the hydrofoils one on each side of the hull forrotary movement in opposite directions about near-vertical axes fore andaft of the hull, means mounting the hydrofoils for rotary movement abouthorizontal axes, steering mechanisms mounted on the craft, and meansconnecting the steering mechanism to each of the hydrofoils in a mannersuch that movement of the steering mechanism through a predeterminedsteering range effects opposite fore and aft movement respectively ofsaid pair of hydrofoils for steering the craft, whereas movement of thesteering mechanism beyond the predetermined steering range effectsrotation of the hydrofoils about the horizontal axes to thereby retractthe hydrofoils to positions above the surface of a body of water uponwhich the craft is borne.

8. A hydrofoil craft as set forth in claim 7 wherein the meansconnecting the steering mechanism to the hydrofoils includes means forsimultaneously rotating each of the hydrofoils backward and upwardrelative to the bull to thereby retract the hydrofoils in anup-side-down position substantially in alignment with the sides of thehull.

9. A hydrofoil craft comprising a hull, a pair of hydrofoils forsupporting said craft in motion, means mounting the hydrofoils onforward portions of the hull on opposite sides thereof for rotarymovement in opposite directions fore and aft of athwartship, saidhydrofoils each having a predetermined angle of attack when positionedathwartship, steering mechanism mounted on the craft, and meansconnecting the steering mechanism to each of the hydrofoils in a manneras to rotate the hydrofoils in opposite directions fore and aft ofathwartship by movement of thesteering mechanism to thereby steer thecraft by movement of the hydrofoils.

10. A hydrofoil craft as set forth in claim 9 which includes manuallyoperative means for separately adjusting the angle of attack of each ofthe hydrofoils while the craft is in motion.

- 1-1. A hydrofoil craft as set forth in claim 9 which includes meansoperative by the fore and aft movement of the hydrofoils forautomatically changing the angle of attack of each of the hydrofoils ina manner as to increase the angle of attack of the forwardly moving oroutboard hydrofoil and to decrease the angle of attack of the aft movingor inboard hydrofoil, thus increasing lift of the outboard hydrofoil anddecreasing lift of the inboard hydrofoil while maneuvering a turn,thereby establishing a difference in lift forces of the two hydrofoilswhich difference causes an inboard-banking moment which opposes anoutboard-banking moment of the crafts centrifugal force on the turn.

1 12. A hydrofoil craft as set forth in claim 9 wherein the meansmounting the hydrofoils include means limiting stresses imposed thereonby impact of the hydrofoils with a foreign object.

13. A hydrofoil craft comprising a hull, a pair of hydrofoil mechanismsmounted on near-vertical axes on opposite forward sides of the hull,each of the hydrofoil mechanisms including a frame, a near-verticalshaft mounting said frame on the side of the hull, means releasablysecuring said frame to the near-vertical shaft for rotary movementtherewith and relative thereto, a substantially horizontal shaftrotatably mounted on said frame for rotary movement therewith andrelative thereto, a hydrofoil mounted on said horizontal shaft forrotary' movement therewith, steering mechanism mounted on said craft,and means operatively connecting the steering mechanism to each of thehydrofoil mechanisms in a manner such that movement of the steeringmechanism in one direction causes forward rotary movement of onehydrofoil mechanism about its near-vertical axis and aft rotary movementof the other hydrofoil mecha- -nism about its near-vertical axis,whereas movement of the steering mechanism in an opposite directioncauses opposite fore and aft movements of the hydrofoil mechamsms.

14. A hydrofoil craft as set forth in claim 13 wherein the meansreleasably securing the frame to the nearvertical shaft includes meansoperable upon rotation of such shaft beyond a predetermined steeringrange for releasing the securing means and thereby afford rotarymovement of the frame about the near-vertical shaft, means included inthe steering mechanism for rotating the frame about the near-verticalshaft, and means operable upon movement of the frame about thenear-vertical shaft for rotating the horizontal shaft and attachedhydrofoil relative to the frame to thereby retract the hydrofoil to anup-side-down position clear of a body of water upon which the craft isborne.

15. A hydrofoil craft as set forth in claim 13 wherein the steeringmechanism includes a steering Wheel, and wherein the means connectingthe steering mechanism to each of the hydrofoil mechanisms includes ahydraulic system having means incorporated therein for moving thehydrofoils through a predetermined steering range fore and aft of thehull upon predetermined rotation of the steering wheel and forretracting the hydrofoils upon rotation of the steering wheel beyond thesteering'range.

16. A hydrofoil craft comprising a hull, a pair of hydrofoils forsupporting the craft in motion, means mounting said hydrofoils onopposite sides of the hullfor rotary movement in opposite directionsfore and aft of athwartship, steering mechanism mounted on the craft,means connecting the steering mechanism to each of said hydrofoils forsimultaneous movement thereof fore and aft of athwartship to therebysteer the craft by the hydrofoils, each of said hydrofoils beinositioned in a common near-vertical plane when athwartship, and saidmounting means including a support attached to an upper portion of eachof the hydrofoils and extending aft of the near-vertical plane, theconstruction and arrangement of the hydrofoils and the mounting meansbeing such that in flight the lift forces of each of the hydrofoils tendto rotate the bottoms thereof forward to thereby counterbalance theeffect of drag forces tending to rotate the bottoms aft therebyproviding a cushion effect for impact on the hydrofoils.

17. A hydrofoil craft as set forth in claim 16 wherein the mountingmeans include yieldable means for limiting impact stresses on thehydrofoils and mounting means resulting from impact of the hydrofoilswith foreign objects.

References Cited in the file of this patent UNITED STATES PATENTS1,095,166 Richardson Apr. 28, 1914 2,708,894 Hook May 24, 1955 2,795,202Hook June 11, 1957 FOREIGN PATENTS 738,333 Great Britain Oct. 12, 1955

